Aero engine assembling is the last sector in the manufacturing process of an aero engine, and is also one of the most important manufacturing sectors. Under existing aero engine design and processing technology conditions, the quality and the working efficiency of the assembling make great contributions to the quality, performance and working efficiency of the engine. Therefore, during the assembling, the coaxality of the rotor after being mounted should be increased as much as possible, thereby reducing the vibration of the aero engine and improving the performance of the aero engine. However, in real production, the assembling of the aero engine is completely hand-assembled, and the accuracy degree and the stability of the assembling depends entirely on the operational experience and technical level of the assembling workers, therefore, there is a lack of a fast and efficient method that guides the assembling of the aero engine rotor, improves the assembling efficiency, reduces the vibration of the aero engine and improves the performance of the aero engine.
With the development of the aero engine assembling test technology, the aero engine assembling test technology gets more and more attention and becomes the research hotspot. More and more researchers hold in-depth discussions about the aero engine rotor, and Rolls-Royce PLC proposed a scheme (System and method for improving the damage tolerance of a rotor assembling. The European Patent Publication Number: EP 2525049 A2), which is mainly that: each sub test system obtains the stress signal of each position of the rotor, the main system analyzes the signals collected by each sub system, and analyzes the influence on the assembling from damage tolerance parameters of each rotor, thereby improving the assembling of the aero-engine rotor. This method has the following problem: the influence of the aspect of the geometric quantity of the rotor on the assembling is not analyzed, therefore, it is impossible to improve the influence of the geometric quantity on the assembling.
Xi'an Jiaotong University proposed a method for detecting the aero engine rotor assembling performance (A method for detecting the aero engine rotor assembling performance. Publication Number: CN101799354A). The method first uses exciter to excite the aero engine rotor, and obtains a multi-carrier coupled impulse response signal of the aero engine rotor by using a vibration sensor and a signal collecting system software; and then, analyzes the obtained multi-carrier coupled impulse response signal of the aero engine rotor by using the dual tree complex wavelet transform method, so as to obtain eight single-carrier impulse response sub-signal of the aero engine rotor; finally, extracts the average assembling performance index from the obtained eight single-carrier impulse response sub-signal of the aero engine rotor, wherein, if the obtained average assembling performance index value is greater than or equal to 10, it is determined that the assembling of the aero engine rotor is qualified, and if the obtained average value is less than 10, it is determined to be unqualified, and then it is necessary to rework and repair. This method has the following problem: there is no guidance for assembling the aero engine rotor.
LUOXIN PRECISION PART (Shanghai) Co., Ltd proposed a device for measuring coaxality (A coaxality measuring device. Publication Number: CN202024752U). This device includes a pair of driving spindles provided on the main body of the device and whose rotation is synchronically controlled by a synchronization mechanism, and the inner ends of the driving spindle are correspondingly provided with a probe and a positioning reference plane respectively; a sensor probe is provided above the position between the probes. It mainly achieves the measurement of the coaxality and jitter of the existing precision parts. This method has the following problem: only the coaxality of the measured part is measured, and the problem of poor coaxality after the rotor is assembled is not solved.
Shenyang Liming Aero-Engine (Group) Co., Ltd. proposed a gap measurement method (A non-contact measurement method for the radial gap of the engine rotor blade tips. Publication Number: CN102175135A). This method uses measurement techniques of capacitance method, and the measuring steps are as follows: at first, assembling the measurement system, calibrating the sensor, and setting the relationship between the radial gap of the blade tips and the voltage, and then, fixing the sensor on the blade, finally, measuring the radial gap of the engine rotor blade tips. This method has the following problem: the influence of the axial mounting plane during the assembling the rotor to the assembled rotor is not considered.
The test object of the aero engine assembling is a turbine stator and a rotor, and under the condition that the part processing precision satisfies the requirement, the final test result is determined by the state after mounting and fitting, whereas the assessment index is mainly the coaxality parameter of the rotor after assembling. The rotation of the engine generates high pressure, and its rotor is constituted by a plurality of single components combined together, wherein, it is the most ideal when the rotary shaft of each component coincides with the axis of the entire engine. The high-speed rotation speed of the high-performance engine is larger than 10000 rpm when it is working, and the axial or radial deflection of the single component will inevitably result in that the center of the turbine disk offsets from the rotation axis of the engine, therefore, a very large centrifugal force will be generated under such condition, which will lead to unbalance of the rotor rotation and lead to engine vibration, thereby ensuring that the coaxality after each component is assembled is the important and difficult issue to be solved during mounting.
As for a model assembling without using coaxality optimization method, due to processing precision limitations, there are errors in the axial direction and radial direction of each component, such as jitter, eccentricity, inclination and so on. If it is assembled directly and randomly, so it may have the case that a bending similar to the “banana” is formed, that is, the eccentricity and inclination errors of each lower component are accumulated to the upper component, resulting in entire deflection and great inclination after the assembling, and leading to poor coaxality of the engine rotor, and therefore, it is difficult to satisfy application requirements
At present, the domestic engine assembling still adopts traditional assembling method which is dominated by manually testing with a dial gauge. The engine is assembled in accordance with the order from the bottom to the top, and measurement is done right after one component is assembled so as to ensure that the entirety after adding a component each time can satisfy the threshold conditions of the coaxality, and then another component is mounted upwardly. Each time, the previous component is taken as a reference, and finally, the coaxality of the entirety is required to be within a certain range. This method is time consuming, and the possibility to rework is large, which affects the mounting efficiency and the one-time success rate, and usually, the one-time successful assembling needs 4-5 days. Moreover, since the position is not the optimal assembling position, it usually requires dismounting 4-5 times and also requires the workers to assemble with rich experience, and each assembling needs to go through hot working and cold working. Thus, the current aero engine assembling method has low mounting efficiency, and it is difficult to mount. Besides, the coaxality is poor after assembling, which affects engine performance.